A series of experiments is proposed to investigate sensory and perceptual processes in speech communication. These experiments will attempt to clarify the mechanisms of perceptual organization of the speech signal, which operate early in the processing of acoustic stimuli. The processes that organize phonetic signals define coherent patterns of stimulus elements, establishing an auditory representation appropriate for phonetic recognition. Psychophysical research on auditory organization provides one source of hypotheses about the treatment of speech stimuli. In this vein, current concepts of frequency analysis will be applied to the identification of sentence intonation, with specific reference to the concept of the dominance region in pitch perception. The proposed research also seeks to extend the analysis of auditory streaming to include the organization of speech signals. The projects examine the integration of concurrent variations in formant frequency; the basis for perceptual continuity when stimulus elements in the speech stream are physically discontinuous; and the contribution of the perceiver's knowledge of natural spectrotemporal signal changes in these processes. The organizing effects of lexical structure will also be investigated. These studies will identify the means by which the perceptual integrity of the speech signal is established and maintained, thereby contributing to our understanding of speech perception by normal human adults.